grub menu is automatically skipped

[Greg Woods]

On Mon, 2010-08-23 at 11:36 -0500, Mikkel wrote:

> Grub is a general purpose boot loader. It does not know how to check
> if there is an OS hibernating. I should also add that if the BIOS
> supports it, and Linux know how to use it, it will resume directly
> from disk without Grub ever entering the picture.

I will have to look in the BIOS and try to figure out which boot
parameter controls this. Something definitely knows that the system has
hibernated, because the immediate boot to Linux only happens after I
have hibernated. Suspending is of course a different deal, since resume
can only work with help from the BIOS. If a boot loader is loaded into
memory, the suspended image would be overwritten. A hibernated image can
be preserved even across booting an entirely different OS.

> 
> With Windows, you normally have to set it up before you can use it.

I think there has to be a hibernate partition. Windows doesn't normally
have a swap partition the way Linux does, so Linux just uses the swap
partition to store the hibernated image. If you have a Linux system
without swap, you won't be able to hibernate.

> I am not sure about Linux. I don't hibernate my systems often enough
> to look into all the fancy options.

The boot option is "resume=/dev/<swap-partition-device)". This also
tells the kernel to use that swap partition for the hibernated image. I
have even had multiple versions of Linux hibernated at the same time,
which works as long as each has a different swap area. 

A system that is having trouble resuming can bypass the hibernated image
and boot from scratch if "noresume" is given instead.

--Greg